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"A study was performed on a laser-induced shock wave plasma generated on high concentration Au-Ag-Cu alloys by a Q-switched Nd-YAG laser of 4.8 mJ under reduced air pressure of 2 Torr. It was found that the total emission intensity of the secondary plasma is proportional to the intensity of the primary plasma, Assuming linear proportionality between the intensity of the primary plasma and the number of atoms vaporized from the target, it is proposed that the quantitative analysis can be applied to the intensities of the analytical emission Iines normalized by the total intensity of the primary plasma. This experimental result demonstrated for each metal element shows an excellent linear relationship between the normalized emission line intensity and the content of corresponding element after primary plasma normalization."

"ABSTRAKTujuan dari eksperimen yang dilakukan adalah untuk menyelidiki hal-hal yang berkaitan dengan pembentukan plasma, yakni zat yang tersusun dari muatan-muatan listrik bebas berupa ion-ion positif dan elektron elektron negatif yang jumlahnya nyaris sama.Plasma yang digunakan dalam eksperimen terbentuk dari udara laboratorium yang di iradiasi dengan berkas laser energi tinggi ( IJ - 2J ) dalam sebuah chamber yang dilengkapi dengan suatu rangkaian listrik DC.Dengan memberikan beda tegangan tertentu antara dua elektrode yang berada dalam chamber, maka elektron-elektron dari plasma yang berada diantara kedua elektrode tersebut akan ditarik oleh elektrode positif dan menimbulkan arus listrik pada resistor yang ada dalam rangkaian. Besar arus listrik yang mengalir ini dapat ditentukan harganya dengan cara mengukur besar tegangan pada resistor menggunakan cathode ray oscilloscope.Chamber yang merupakan kotak tertutup berisi plasma yang diamati, dilengkapi dengan pengukur tekanan, dan di hubungkan ke sebuah pompa vakum.Dengan memvariasi besar tekanan udara dalam chamber, jarak antar elektrode, beda tegangan antara elektrode, maupun besar energi laser, dapat diperoleh harga besaran-besaran fisis yang diselidiki, juga korelasi-korelasi antara suatu besaran fists, dengan besaran fists lainnya.

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ABSTRACT

An investigation has been conducted on the formation of plasma generated by focusing an intense Laser radiation.

A high voltage from DC source is used to trigger electrical breakdown between two electrodes which an air of laboratory will be investigated.

The electrical breakdown caused by laser radiation observed by measuring the voltage of pick up resistor in the electrical circuit. The value of electric current flows in resistor can be calculated from the value of voltage, it expresses the amount of electrons flow from plasma. By variating air pressure in the chamber, distance between two electrodes, potential difference between two electrodes, and laser energy, we can find correlations between: air pressure versus breakdown probability, air pressure versus electron number density, Laser energy versus electron number density, electric field per pressure versus electron drift velocity, etc."

"A TEA CO2 laser pulse (50 mJ, 100 ns) was focused under reduced pressure on the silicone grease painted on copper plate as a sub-target with a power density of 6 GW/cm2. The comparison was made on the characteristics of the induced laser plasma between the two cases, with sub-target and without sub-target. It is proved that emission spectrum assigned to silicone atom can be detected only for the case with sub-target. It is also proved that in the absence of the sub-target, the gushing speed of the atoms is very low, while for the case with sub-target, the gushing speed of atoms becomes very fast. It is shown that the setting of sub-target is very effective to make laser-induced shock-wave plasma and it is very effective to realize quantitative analysis of soft material."

"Mekanisme plasma yang dibangkitkan oleh Laser Nd-YAG pada sampel padat pada tekanan udara di bawah 1 Torr akan dilakukan. Dalam hal menganalisis sifat-sifat plasma ini akan dilakukan perbandingan dengan karakteristik plasma pada tekanan udara di atas 1 Torr. Eksperimen sementara menunjukkan bahwa sifat-sifat plasma pada tekanan di bawah 1 Torr mempunyai mekanisme yang lain dengan plasma pada tekanan tinggi. Plasma pada tekanan udara di bawah 1 Torr dapat diprediksi karena proses tumbukan sangat cepat sebaliknya pada tekanan tinggi karena proses gelombang kejut (shock wave). Eksperimen menunjukkan bahwa plasma pada tekanan udara 0,5 Ton mempunyai slop posisi fungsi waktu mendekati satu dan mempunyai cacah latar (background) yang rendah."

"A special interferometric technique with high sensitivity has been devised on the basis of rainbows refractometer without the use of an additional and delicate amplitude-splitting setup. This new technique was use for the characterization of shock wave plasma induced by a Q-sw Nd-YAG laser on various kinds of metal samples under reduced gas pressures. An unmistakable signal of density jump was detected simultaneously with the emission front signal. It is proved that at the initial stage of the secondary plasma expansion, the front of the emission and the front of the blast wave was coincide and move together with time. However, at a later stage, the front of the emission will separate from that of the blast wave induced in the surrounding gas at low pressures. Using Cu and Zn samples, the experimental result showed that the separation of the emission front and blast wave front took place at 4 mm above sample surface for the laser energy of 140 mJ."

"ABSTRACTAn comprehensiove study has been carried out for the study and extension of lases induce shock wave plasma spectroscopy (LISPS) application to non metalic soft and hard samples. For this purpose, a series of experiments were conducted to investigate the dynamical process taking place in the laser plasma generated by a high power and short pulse laser irradiations on a non metal soft and hard samples it was found that in the case of non metal soft sample, the ablated atoms failed to induce a visible plasma at the surface of the target however, it became possible, after a few laser shots depending on the target layer thickness, to generate the sock wave plasma emitting the characteristic spectral line of the target material.Another related phenomenon studied in this experiment is the pre-irradiation effect pbserved on a non metal hard sample such as quartz sample, which was characterized by absence of secondary plasma at athe initial shots. The disappearance of this effect at a later stage was found to be connected with the appearance of a crater of appropriate depth on the sample surface created by iniatial repeated irradiations on the sample surface. The plasma produced thereafter exhibited typical features of a secondary plasma. Further experiment employing aaratificial ring crater on the sample surface has eliminated the pre-irraduation effect completely, and has thus demonstrated that it is the confinenement effect of the crater which was solely responsible for the generation of secondary plasma from the non metal hard tearget. This conclusion is ini confrormation with the shock wave proposed earlier.These experimental studies have thus considerably substantiated our understanding of the process of secondary plasma generatuion. In turn, this result helps to improve the quality and extend the scope of LISPS applications in the future"

"ABSTRACTAn comprehensiove study has been carried out for the study and extension of lases induce shock wave plasma spectroscopy (LISPS) application to non metalic soft and hard samples. For this purpose, a series of experiments were conducted to investigate the dynamical process taking place in the laser plasma generated by a high power and short pulse laser irradiations on a non metal soft and hard samples it was found that in the case of non metal soft sample, the ablated atoms failed to induce a visible plasma at the surface of the target however, it became possible, after a few laser shots depending on the target layer thickness, to generate the sock wave plasma emitting the characteristic spectral line of the target material.Another related phenomenon studied in this experiment is the pre-irradiation effect pbserved on a non metal hard sample such as quartz sample, which was characterized by absence of secondary plasma at athe initial shots. The disappearance of this effect at a later stage was found to be connected with the appearance of a crater of appropriate depth on the sample surface created by iniatial repeated irradiations on the sample surface. The plasma produced thereafter exhibited typical features of a secondary plasma. Further experiment employing aaratificial ring crater on the sample surface has eliminated the pre-irraduation effect completely, and has thus demonstrated that it is the confinenement effect of the crater which was solely responsible for the generation of secondary plasma from the non metal hard tearget. This conclusion is ini confrormation with the shock wave proposed earlier.These experimental studies have thus considerably substantiated our understanding of the process of secondary plasma generatuion. In turn, this result helps to improve the quality and extend the scope of LISPS applications in the future"

"In this paper ,the growth of GaN:Mn thin films by plasma-assisted metalorganic chemical vapor deposition (PAMOCVD) method is reported ..."

"This study was designed to optimalize the use of opididymal or ejaculate sperm and plasma for in vitro fertilization,that sperm agglutination was found at preparation. The rate of sperm agglutination was calculated the head-to-head sperm agglutination that were incubated in KR-HEPES medium in 38.5 oC with 5% CO2 at 1,3,5 and 7 hours culture in vitro....."

"ABSTRAKSaat ini teknologi nuklir berkembang dengan baik di Indonesia dan pemanfaatannya baik di bidang kesehatan, pertanian, peternakan, industri dan energi digunakan sepenuhnya untuk kesejahteraan seluruh masyarakat Indonesia. Dalam pengembangan dan pemanfaatan teknologi nuklir tentu harus mempertimbangkan dan meminimalisir efek bahaya dari radiasi nuklir, baik untuk pekerja yang berada dilingkungan instalasi nuklir maupun bahaya kontaminasi lingkungan disekitar instalasi nuklir. Untuk itu kegiatan pemantauan, pendeteksian dan pengukuran radiasi mutlak diperlukan. Umumnya kegiatan pemantauan, pendeteksian dan pengukuran radiasi dilakukan dengan perangkat deteksi nuklir. Pada penelitian kali ini dilakukan metode alternatif pengukuran, analisis dan identifikasi unsur radioaktif dengan teknik laser induced plasma spectroscopy LIPS . Penggunaan teknologi LIPS dipilih karena LIPS adalah suatu teknik analisis sampel secara in situ, kualitatif dan kuantitatif yang cepat, dan hampir tanpa preparasi sampel. Analisis dan identifikasi unsur radiaoaktif dilakukan dengan menembakkan laser pulsa NdYAG Q-Switch 355 nm, 10 Hz, durasi pulsa 5.5 ns, f = 100 mm, dengan variasi energi 5.5 mJ - 140 mJ dan dengan variasi tekanan udara 4 Torr ndash; 1 atm pada sampel material radioaktif alamiah atau Naturally Occurring Radioactive Material NORM dengan metoda ablasi laser yang dilanjutkan dengan metoda spectral plasma analisis. Berdasarkan penelitian yang telah dilakukan, secara kualitatif teknik LIPS mampu mengidentifikasi adanya unsur radioaktif Uranium U dan Thorium Th yang terdapat pada sampel uji dengan energi laser optimum sebesar 107 mJ dan secara kuantitatif didapatkan nilai prediksi konsentrasi unsur Uranium sebesar 155 ppm dengan persentase error 11.3 dan nilai batas deteksi sebesar 7.89 ppm, nilai prediksi konsentrasi unsur Thorium sebesar 124 ppm dengan persentase error 8 dan nilai batas deteksi sebesar 12.4 ppm. Dengan kata lain teknik LIPS secara inheren sangat cocok dan sangat memungkinkan digunakan sebagai teknik pengukuran, analisis dan identifikasi keberadaan unsur radioaktif.

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ABSTRACTNuclear technology is currently well developed in Indonesia and its use in the field of health, agriculture, industry and energy is completely used for the welfare of all the people of Indonesia. In the development and utilization of nuclear technology should certainly consider and minimize the effects of nuclear radiation hazards, both for the workers who are in the environment of nuclear installations and the danger of contamination of the environment around nuclear installations. Therefore monitoring activity, detection and measurement of radiation is absolutely necessary. Generally the monitoring activity, detection and measurement of radiation carried by the nuclear detection devices. In this study, alternative methods of measurement, analysis and identification of radioactive elements is carried out by using laser induced plasma spectroscopy LIPS . The use of LIPS technology is selected since LIPS is a technique in situ sample analysis, qualitative and quantitative fast, and almost no sample preparation. Analysis and identification of the radioactive element is carried out by firing laser pulses NdYAG Q Switch 355 nm, 10 Hz, pulse duration of 5.5 ns, f 100 mm, with a variation of the energy 5.5 mJ 140 mJ and with variations in air pressure 4 Torr 1 atm in a sample of Naturally Occurring Radioactive Material NORM with laser ablation method, followed by plasma spectral analysis method. Based on the research that has been done, LIPS technique is qualitatively able to identify the presence of radioactive elements, i.e. Uranium U and thorium Th contained in the test sample with a laser energy optimum of 107 mJ and quantitatively obtained predictive value of elemental concentrations of Uranium of 155 ppm along with 11.3 of percentage error and 7.89 ppm of detection limit value, also the predictive value of the elemental concentration of thorum of 124 ppm along with 8 of percentage error and 12.4 ppm of detection limit value. In other words, LIPS technique is inherently very suitable and it is possible to use as a measurement technique, analysis and identification of the presence of radioactive materials."